Distinguish between unmatched subpatterns and empty matches in preg_*() #1303
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I think this makes sense. |
php-pulls
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* pull-request/1303: Distinguish between unmatched subpatterns and empty matches in preg_*() news entry for PR #1303
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Thanks :) |
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This needs a note in UPGRADING, as it's BC breaking. |
Done with commit c832ab4. |
gsherwood
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photodude
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wilsonge
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Fixed bug introduced by preg_match change from php/php-src#1303
photodude
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Mar 7, 2017
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BC break, but why? Seriously, not again. |
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Documenting BC breaks is not enough - the policy is not to have them outside major versions. Why not add a flag that controls this behaviour? |
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Agreed, another useless BC break in minor version. Please rather introduce something opt-in like PREG_SUBPATTERN_UNMATCHED_NULL (or whatever better) that could be turned on by default in next major version. |
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Is this behaviour going to stay? or will it change to something BC? |
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This already breaks Symfony: symfony/symfony#22667 |
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See #2526 to make this opt-in, removing the BC break. |
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Currently it is not easily possible to distinguish between unmatched subpatterns (i.e. unset substrings) and empty matches in preg_match(_all); in both cases an empty string is yielded. Using PREG_OFFSET_CAPTURE makes that possible (negative offset indicate unmatched subpatterns), but that seems to be unnecessarily clumsy.
In bug #61780 it has been proposed not to set the respective keys in $matches, but that might be too big a BC break even for PHP 7.0.0. Setting those to NULL, however, might be acceptable, and would still allow to distinguish between the two cases (even with isset). Therefore I think this PR would resolve bug #61780.